cryptsetup/cryptenroll: Iterate over TPM tokens when they don't match

When we enroll two UKIs with different PCR pub keys into one LUKS slot/
token each, then we can encounter the wrong one and should not give up
but continue iterating instead of requiring the passphrase. Similarly,
a pcrlock token might be for another UKI and we should continue the
search. Same for a token that is meant for another TPM (e.g., external
storage). While this is mainly about cryptsetup's automatic unlocking
from the initrd, it also matters for usage in the system, e.g., for
other storage and when cryptenroll should unlock using the TPM.
There are two code paths, one is the libcryptsetup plugin and the other
is the fallback when that's not available.
To let the libcryptsetup loop continue to iterate, remap the above
error conditions to EPERM. For the fallback path check all of them (no
remapping) and continue iteration. For better log output, include the
token ID to be able understand which token fails.

src/cryptsetup/cryptsetup-tokens/cryptsetup-token-systemd-tpm2.c

@@ -23,13 +23,22 @@ _public_ const char *cryptsetup_token_version(void) {
         return TOKEN_VERSION_MAJOR "." TOKEN_VERSION_MINOR " systemd-v" PROJECT_VERSION_FULL " (" GIT_VERSION ")";
 }
 
-static int log_debug_open_error(struct crypt_device *cd, int r) {
+static int log_debug_open_error(struct crypt_device *cd, int token, int r) {
         if (r == -EAGAIN)
                 return crypt_log_debug_errno(cd, r, "TPM2 device not found.");
-        if (r == -ENOSTR)
-                return crypt_log_debug_errno(cd, r, "No matching TPM2 token data found.");
+        if (r == -ENOSTR) {
+                /* Remap to -EPERM so libcryptsetup's CRYPT_ANY_TOKEN loop keeps iterating. */
+                (void) crypt_log_debug_errno(cd, r, "Token %d: no matching TPM2 token data found.", token);
+                return -EPERM;
+        }
+        if (IN_SET(r, -EREMCHG, -EREMOTE)) {
+                /* Remap as above. Note: For now without -EUCLEAN because currently the only error it
+                 * reports won't be solved by moving to another token. */
+                (void) crypt_log_debug_errno(cd, r, "Token %d: TPM policy does not match current system state, skipping.", token);
+                return -EPERM;
+        }
 
-        return crypt_log_debug_errno(cd, r, TOKEN_NAME " open failed: %m.");
+        return crypt_log_debug_errno(cd, r, "Token %d: open failed: %m.", token);
 }
 
 _public_ int cryptsetup_token_open_pin(
@@ -78,8 +87,11 @@ _public_ int cryptsetup_token_open_pin(
                 params = *(systemd_tpm2_plugin_params *)usrptr;
 
         r = sd_json_parse(json, SD_JSON_PARSE_MUST_BE_OBJECT, &v, /* reterr_line= */ NULL, /* reterr_column= */ NULL);
-        if (r < 0)
-                return crypt_log_debug_errno(cd, r, "Failed to parse token JSON data: %m");
+        if (r < 0) {
+                /* Remap to -EPERM so libcryptsetup keeps iterating past a broken token. */
+                (void) crypt_log_debug_errno(cd, r, "Token %d: failed to parse JSON data: %m", token);
+                return -EPERM;
+        }
 
         struct iovec *blobs = NULL, *policy_hash = NULL;
         size_t n_blobs = 0, n_policy_hash = 0;
@@ -104,10 +116,13 @@ _public_ int cryptsetup_token_open_pin(
                         &pcrlock_nv,
                         &flags);
         if (r < 0)
-                return log_debug_open_error(cd, r);
+                return log_debug_open_error(cd, token, r);
 
-        if (params.search_pcr_mask != UINT32_MAX && hash_pcr_mask != params.search_pcr_mask)
-                return crypt_log_debug_errno(cd, ENXIO, "PCR mask doesn't match expectation (%" PRIu32 " vs. %" PRIu32 ")", hash_pcr_mask, params.search_pcr_mask);
+        if (params.search_pcr_mask != UINT32_MAX && hash_pcr_mask != params.search_pcr_mask) {
+                /* Remap to -EPERM so libcryptsetup keeps iterating to the next token. */
+                crypt_log_debug(cd, "Token %d: PCR mask doesn't match expectation (%" PRIu32 " vs. %" PRIu32 ")", token, hash_pcr_mask, params.search_pcr_mask);
+                return -EPERM;
+        }
 
         r = acquire_luks2_key(
                         params.device,
@@ -130,12 +145,12 @@ _public_ int cryptsetup_token_open_pin(
                         flags,
                         &decrypted_key);
         if (r < 0)
-                return log_debug_open_error(cd, r);
+                return log_debug_open_error(cd, token, r);
 
         /* Before using this key as passphrase we base64 encode it, for compat with homed */
         base64_encoded_size = base64mem(decrypted_key.iov_base, decrypted_key.iov_len, &base64_encoded);
         if (base64_encoded_size < 0)
-                return log_debug_open_error(cd, base64_encoded_size);
+                return log_debug_open_error(cd, token, base64_encoded_size);
 
         /* free'd automatically by libcryptsetup */
         *ret_password = TAKE_PTR(base64_encoded);

src/cryptsetup/cryptsetup.c

@@ -2181,7 +2181,10 @@ static int attach_luks_or_plain_or_bitlk_by_tpm2(
                                                 &decrypted_key);
                                 if (IN_SET(r, -EACCES, -ENOLCK))
                                         return log_notice_errno(SYNTHETIC_ERRNO(EAGAIN), "TPM2 PIN unlock failed, falling back to traditional unlocking.");
-                                if (r != -EPERM)
+                                /* Stop unless we should keep iterating to next token because the tried one
+                                 * does not match boot state. For now without -EUCLEAN because currently the
+                                 * only error it reports won't be solved by moving to another token. */
+                                if (!ERRNO_IS_NEG_TPM2_TOKEN_MISMATCH(r))
                                         break;
 
                                 token++; /* try a different token next time */